Potential metabolic biomarkers of critical limb ischemia in people with type 2 diabetes mellitus.

INTRODUCTION: Type 2 diabetes mellitus (T2DM) is a significant risk factor for the development of critical limb ischemia (CLI), the most advanced stage of peripheral arterial disease. The concurrent existence of T2DM and CLI often leads to adverse outcomes, namely limb amputation. OBJECTIVE: To identify biomarkers for improving the screening of CLI in high-risk people with T2DM. METHODS: We investigated metabolome profiles in serum samples of 113 T2DM people with CLI (n = 23, G2) and without CLI (n = 45, G0: no lower limb stenosis (LLS) and n = 45, G1: LLS < 50%), using hydrogen nuclear magnetic resonance (1H NMR) approach. Principle component analysis (PCA) and partial least squares-discriminant analysis (PLS-DA) were used to analyze 1H NMR data. RESULTS: Twenty potential metabolites that could discriminate people with T2DM and CLI (G2) from non-CLI patients without LLS (G0) were determined in serum samples. The correct percent of classification for the PLS-DA model for the test set samples was 85% (n = 20) and 100% (n = 5) for G0 and G2 groups, respectively. Non-CLI patients with LLS < 50% (G1) were projected on the PCA abstract space built using 20 discriminatory metabolites. Eleven people with T2DM and LLS < 50% were prospectively followed, and their ankle-brachial index (ABI) was measured after 4 years. A promising agreement existed between the PCA model's predictions and those obtained by ABI values. CONCLUSION: The findings suggest that confirmation of blood potential metabolic biomarkers as a complement to ABI for screening of CLI in a large group of high-risk people with T2DM is needed.

A phantom study: Evaluation of a novel three-lumen balloon catheter for potential treatment of intractable limb ischemia.

Critical limb ischemia (CLI) is the most severe form of peripheral arterial disease (PAD) which induces extremity rest pain, extremity gangrene or ulcers that mostly might lead to limb loss. One of the most common criteria of CLI is 50 mmHg or less systolic ankle arterial pressure. In this study, a custom made three-lumen catheter (9 Fr) including a distal inflatable balloon in between the inflow and outflow lumen holes was designed and fabricated based on the patented design of Hyper Perfusion Catheter. The proposed catheter design aims to increase ankle systolic pressure to 60 mmHg or more to promote healing and/or alleviating severe pain due to intractable ischemia for patients with CLI. To simulate the blood circulation of related anatomy, in vitro CLI model phantom was designed and constructed by using a modified hemodialysis circuit, a hemodialysis pump and a tube set for cardio-pulmonary bypass surgery. A blood mimicking fluid (BMF) with dynamic viscosity of 4.1 mPa.s was used at 22 ºC to prime the phantom. The data was collected by a custom-made circuit design in real time and all measurements were verified with commercial certificated medical devices. The results of in vitro CLI model phantom experiments have shown that it is feasible to elevate the pressure distal to the occlusion (representing ankle pressure) above 80 mmHg without affecting the systemic pressure.

Clinical outcomes of chronic limb-threatening ischemia due to inflammatory nonatherosclerotic versus atherosclerotic etiologies undergoing revascularization.

BACKGROUND: The scope of clinical guidelines for the management of chronic limb-threatening ischemia (CLTI) is limited to atherosclerotic disease of the lower-extremity arteries. This study aimed to reveal the clinical features and prognoses of CLTI due to inflammatory nonatherosclerotic etiologies undergoing revascularization. METHODS: DECOPON (DatabasE of ChrOnic limb-threatening ischemia Presenting ischemic ulcer and gangrene due to nON-atherosclerotic disease) is a multicenter retrospective study that evaluated 465 limbs of 414 patients with CLTI undergoing revascularization for ischemic tissue loss with inflammatory nonatherosclerotic etiologies between 2010 and 2020. Clinical features and prognoses were compared with 930 limbs of 809 patients with atherosclerotic CLTI during the same period. RESULTS: The frequency of conventional atherosclerotic risk factors was significantly lower in the inflammatory nonatherosclerotic group. The inflammatory nonatherosclerotic group had more severe WIfI (wound, ischemia, and foot infection) W and fI grades, and more frequent infrapopliteal and inframalleolar artery diseases with a rarer presence of arterial calcification (all p < 0.05). Adjunctive therapy was more frequently performed in the inflammatory nonatherosclerotic group (p < 0.05). The inflammatory nonatherosclerotic group had a lower incidence rate of wound healing (0.64-fold, p < 0.001) and a higher incidence rate of major reintervention (2.30-fold, p = 0.006), whereas the risk ratio of all-cause mortality was 0.83-fold (p = 0.067). The association of inflammatory nonatherosclerotic disease with the delayed wound healing and the susceptibility to major reintervention remained significant even after adjustment for covariates (both p < 0.001). CONCLUSIONS: Patient, limb, and lesion characteristics of inflammatory nonatherosclerotic CLTI were considerably different from those of atherosclerotic CLTI. Inflammatory nonatherosclerotic CLTI was less likely to heal than atherosclerotic CLTI.

Endothelial Progenitor Cells May Be Related to Major Amputation after Angioplasty in Patients with Critical Limb Ischemia.

BACKGROUND: Critical limb ischemia represents an advanced stage of peripheral arterial disease. Angioplasty improves blood flow to the limb; however, some patients progress irreversibly to lower limb amputation. Few studies have explored the predictive potential of biomarkers during postangioplasty outcomes. AIM: To evaluate the behavior of endothelial progenitor cells in patients with critical limb ischemia, in relation to their postangioplasty outcome. METHODS: Twenty patients with critical limb ischemia, candidates for angioplasty, were enrolled. Flow-mediated dilation, as well as endothelial progenitor cells (subpopulations CD45+/CD34+/CD133+/CD184+ and CD45+/CD/34+/KDR[VEGFR-2]+ estimated by flow cytometry) from blood flow close to vascular damage, were evaluated before and after angioplasty. Association with lower limb amputation during a 30-day follow-up was analyzed. RESULTS: Endothelial progenitor cells were related with flow-mediated dilation. A higher number of baseline EPCs CD45+CD34+KDR+, as well as an impaired reactivity of endothelial progenitor cells CD45+CD34+CD133+CD184+ after angioplasty, were observed in cases further undergoing major limb amputation, with a significant discrimination ability and risk (0.75, specificity 0.83 and RR 4.5 p < 0.05). CONCLUSIONS: Endothelial progenitor cells were related with endothelial dysfunction, whereas a higher baseline number of the subpopulation CD45+CD34+KDR+, as well as an impaired reactivity of subpopulation CD45+CD34+CD133+CD184+ after angioplasty, showed a predictive ability for major limb amputation in patients with critical limb ischemia.

Fasudil, a ROCK inhibitor, preserves limb integrity in a mouse model of unilateral critical limb ischemia: Possible interplay of inflammatory and angiogenic signaling pathways.

Peripheral arterial diseases (PAD) had a great attention owing to devastating consequences of disability and cardiovascular morbidity and mortality. Yet, current therapeutic options are limited to surgical revascularization with no effective pharmacotherapy available. Excessive activity of Rho-associated coiled-coil protein kinase (ROCK) is implicated with several vascular diseases, rendering ROCK inhibition as a potential therapeutic strategy for patients suffering vascular disorders. AIM: The current study was dedicated to investigating the vascular protective potential of Fasudil, a ROCK inhibitor, on an experimentally induced unilateral critical limb ischemia (CLI) model in mice and demonstrated the possible underlying mechanisms. METHODS: Unilateral CLI was induced by ligation and excision of femoral artery followed by daily i.p. injection of Fasudil (10 mg/kg or 25 mg/kg) up to two weeks post-surgery. KEY FINDINGS: Mice underwent CLI showed decreased antioxidant capacity and increased inflammatory signal, evident by elevation of ERK1/2 in both serum and GC muscles that coincided with increases in VEGFA, HIF-1α and CD34+ cells of GC muscles. CLI resulted in structural damage of GC muscle fibers, with marked apoptosis, declined proliferation and deteriorated peripheral limb function. Treatment with Fasudil restored antioxidant capacity and attenuated VEGFA, HIF-1α, CD34+ cells and inflammatory markers in ischemic limbs. Furthermore, Fasudil preserved histological integrity of ischemic GC muscles, with amelioration of apoptosis, preserved proliferation rate and improvement in peripheral limb function. SIGNIFICANCE: Fasudil could protect against experimentally induced unilateral CLI, in a dose-dependent manner, which could pave the way for future clinical application of Fasudil in patients suffering PAD.

Therapeutic angiogenesis-based strategy for peripheral artery disease.

Peripheral artery disease (PAD) poses a great challenge to society, with a growing prevalence in the upcoming years. Patients in the severe stages of PAD are prone to amputation and death, leading to poor quality of life and a great socioeconomic burden. Furthermore, PAD is one of the major complications of diabetic patients, who have higher risk to develop critical limb ischemia, the most severe manifestation of PAD, and thus have a poor prognosis. Hence, there is an urgent need to develop an effective therapeutic strategy to treat this disease. Therapeutic angiogenesis has raised concerns for more than two decades as a potential strategy for treating PAD, especially in patients without option for surgery-based therapies. Since the discovery of gene-based therapy for therapeutic angiogenesis, several approaches have been developed, including cell-, protein-, and small molecule drug-based therapeutic strategies, some of which have progressed into the clinical trial phase. Despite its promising potential, efforts are still needed to improve the efficacy of this strategy, reduce its cost, and promote its worldwide application. In this review, we highlight the current progress of therapeutic angiogenesis and the issues that need to be overcome prior to its clinical application.

Variability in 30-day major amputation rates following endovascular peripheral vascular intervention for critical limb ischemia.

Introduction: Patients with critical limb ischemia (CLI) can undergo endovascular peripheral vascular intervention (PVI) to restore blood flow and decrease risk of amputation. As a potential indicator of quality for CLI care, we sought to describe 30-day major amputation rates following PVI. We also examined rate variability, and patient-level and site-level factors predicting amputations, using a national electronic health record (EHR) database. Methods: Using the Cerner Health Facts de-identified EHR database, patients with CLI diagnosis codes undergoing PVI were identified. The rate of amputation within 30 days of PVI was calculated. Risk ratios predicting amputation were derived using a mixed effects Poisson regression model adjusting for 16 patient and clinical factors. Median risk ratios (MRRs) were calculated to quantify site-level variability in amputations. Results: A total of 20,204 PVI procedures for CLI from 179 healthcare sites were identified. Mean age at procedure was 69.0 ± 12.6 years, 58.0% were male, and 29.6% were persons of color. Amputation within 30 days of PVI occurred after 570 (2.8%) procedures. Malnutrition, previous amputation, diabetes, and being of Black race were predictors of amputation. Amputation rates across sites ranged from 0.0% to 10.0%. The unadjusted MRR was 1.40 (95% CI 1.35-1.46), which was attenuated after adjusting for patient-level factors (MRR 1.30, 95% CI 1.26-1.34) and site characteristics (MRR 1.11, 95% CI 1.09-1.13). Conclusions: Among PVI procedures for CLI treatment, 30-day amputation rates varied across institutions. Although patient-level factors explained some variability, site-level factors explained most variation in the rates of these outcomes.

Improvement in walking impairment following surgical and endovascular revascularization: Insights from VOYAGER PAD.

BACKGROUND: Peripheral artery disease (PAD) affects 200 million people worldwide and is associated with impaired quality of life, increased morbidity, and mortality. Supervised exercise therapy (SET) and lower-extremity revascularization (LER) are both proven strategies to improve patient symptoms. Short and long-term functional outcomes after LER for symptomatic PAD in a large, international cohort have not previously been described. METHODS: The VOYAGER PAD trial (ClinicalTrials.gov identifier: NCT02504216) enrolled subjects after LER for symptomatic PAD (Rutherford category 2-6). Participants completed the Walking Impairment Questionnaire (WIQ) at baseline, 1, 3 and 6 months, and every 6 months thereafter. The primary outcome analysis was degree of difficulty walking two blocks at each of the aforementioned time points. Difficulty walking three blocks and climbing one flight of stairs at these time points was also analyzed. Data about supervised and home exercise therapy before or after revascularization were not collected in the VOYAGER PAD trial. RESULTS: Of the 5614 VOYAGER PAD participants completing the WIQ at baseline, three-quarters presented with claudication and one-quarter with critical limb ischemia. Of these, the majority (62% with claudication and 74% with CLI) reported inability or much difficulty walking two blocks prior to LER. Walking improved after LER regardless of revascularization strategy, but one-fifth with claudication and one-third with CLI reported continued inability or much difficulty walking two blocks 1 month after LER. Participants who reported improved walking ability 1 month after LER experienced a durable functional result out to 3 years. Although the proportion of participants reporting significant baseline difficulty climbing one flight of stairs or walking three blocks differed, the trend in immediate and sustained improvement after LER was similar to that observed for walking two blocks. CONCLUSION: In this large, international cohort undergoing LER for symptomatic PAD, nearly two-thirds reported inability or much difficulty walking two blocks at baseline. Although many participants reported improved walking ability after LER, a substantial proportion remained severely disabled. These observations may help motivate providers, patients, and medical systems to improve awareness and engagement in SET referral after LER.

Propensity-matched analysis does not support angiosome-guided revascularization of multilevel peripheral artery disease (PAD).

BACKGROUND: This retrospective comparative cohort study evaluated the clinical outcome of angiosome-guided endovascular arterial reconstructions in chronic limb-threatening ischemia (CLTI) due to multilevel peripheral artery disease (PAD). METHODS: Patients treated in an endovascular fashion for CLTI with tissue loss due to multilevel PAD were analyzed. Limbs were classified as having undergone either angiosome-guided (direct) revascularization (DR) or nonangiosomic (indirect) revascularization (IR). DR was defined as uninterrupted in-line flow to the affected angiosome, revascularization through the pedal arch was also considered direct. Groups were adjusted with propensity score (PS) matching and compared for amputation-free survival (AFS), freedom from major adverse limb events (MALE), and healing rate at 12 months. RESULTS: A total of 174 patients (81 men, mean age 70.0 ± 10.4 y) were included. PS matching produced two groups of 55 patients each: DR (24 men, mean age 71.7 ± 10.7 y) and IR (26 men, mean age 72.0 ± 9.4 y). The matched groups had no significant differences in baseline variables. At 12 months there were no significant differences in AFS (73.2% vs 71.6%; p = 0.841), freedom from MALE (71.7% vs 66.1%; p = 0.617), and healing rate (72.7% vs 72.0%; p = 1.000) between DR and IR, respectively. CONCLUSION: This study failed to support the use of angiosome concept in CLTI due to multilevel disease.

Impact of high on-treatment platelet reactivity after angioplasty in patients with critical limb ischemia.

OBJECTIVES: Dual antiplatelet therapy (DAPT) with aspirin and clopidogrel is standard of care in patients with peripheral artery disease (PAD) after percutaneous transluminal angioplasty (PTA). However, high on treatment platelet reactivity (HTPR) to DAPT is frequent and associated with major adverse limb events (MALE) in PAD patients. Nevertheless, association of MALE and HTPR in patients with critical limb ischemia (CLI) is not known. Moreover, comorbidities might confound response to antiplatelet medication further. Hence, in this trial we analyzed pharmacodynamic responses to DAPT and clinical events in CLI patients post PTA. METHODS: In this prospective single center pilot analysis, we included 71 CLI patients. Patients received DAPT after PTA. Antiplatelet effect were measured by light transmission aggregometry (LTA) and vasodilator-stimulated protein phosphorylation assay (VASP). MALE, major adverse cardiac and cerebrovascular events (MACCE) and BARC bleeding within 12 months follow-up were assessed. RESULTS: Mean age of patients was 73.37 ± 7.36 years and 47 (66.2%) were male. Overall HTPR appeared in 46 patients (64.8%). MALE and MACCE showed no differences between patients with and patients without HTPR. However, bleeding was higher in patients with sufficient pharmacodynamic response to DAPT (Bleeding - HTPR: 13.4% vs. no HTPR: 36.0%; log-rank HR: 0.32; 95% CI 0.1079 to 0.9396 p = 0.0217). This finding remained robust in multivariate analysis. CONCLUSION: HTPR to DAPT is frequent in CLI patients. However, bleeding was higher in patients with sufficient response to DAPT. Ischemic events did not differ. Hence, CLI patients might benefit from an alternative antithrombotic approach.

Clinical practice patterns and ascertainment bias for cardiovascular events in a randomized trial: A survey of investigators in the BEST-CLI trial.

Ascertainment bias is a well-recognized source of bias in research, but few studies have systematically analyzed sources of ascertainment bias in randomized trials in which blinding is not possible and endpoint assessment is not protocolized. In the current study, we sought to evaluate differences in the clinical practice patterns of trial investigators with respect to bias in the ascertainment of pre-revascularization patient risk and the incidence of secondary endpoints post-revascularization. We conducted a cross-sectional survey of active investigators (n = 936) from the Best Endovascular Versus Best Surgical Therapy for Patients with Critical Limb Ischemia (BEST-CLI) trial. The total survey response rate was 19.6% (183/936). Vascular surgeons were more likely than nonsurgical interventionalists to order tests for cardiac complications after both surgical bypass (p < 0.001) and endovascular revascularization (p = 0.038). Post-procedure, investigators were more likely to order additional testing for cardiac complications in open surgery versus endovascular cases (7% vs 16% never, 41% vs 65% rarely, 43% vs 17% sometimes, 9% vs 2% always, respectively; p < 0.0001). Significant variation in practice patterns exist in the pre- and post-procedure assessment of cardiac risk and events for patients with CLI undergoing revascularization. Variation in the ascertainment of risk and outcomes according to the type of revascularization procedure and physician specialty should be considered when interpreting the results of clinical studies, such as the BEST-CLI trial. ClinicalTrials.gov Identifier: NCT02060630.

Racial differences in the limb skeletal muscle transcriptional programs of patients with critical limb ischemia.

Critical limb ischemia (CLI) is the most severe manifestation of peripheral artery disease (PAD) and is characterized by high rates of morbidity and mortality. As with most severe cardiovascular disease manifestations, Black individuals disproportionately present with CLI. Accordingly, there remains a clear need to better understand the reasons for this discrepancy and to facilitate personalized therapeutic options specific for this population. Gastrocnemius muscle was obtained from White and Black healthy adult volunteers and patients with CLI for whole transcriptome shotgun sequencing (WTSS) and enrichment analysis was performed to identify alterations in specific Reactome pathways. When compared to their race-matched healthy controls, both White and Black patients with CLI demonstrated similar reductions in nuclear and mitochondrial encoded genes and mitochondrial oxygen consumption across multiple substrates, indicating a common bioenergetic paradigm associated with amputation outcomes regardless of race. Direct comparisons between tissues of White and Black patients with CLI revealed hemostasis, extracellular matrix organization, platelet regulation, and vascular wall interactions to be uniquely altered in limb muscles of Black individuals. Among traditional vascular growth factor signaling targets, WTSS revealed only Tie1 to be significantly altered from White levels in Black limb muscle tissues. Quantitative reverse transcription polymerase chain reaction validation of select identified targets verified WTSS directional changes and supports reductions in MMP9 and increases in NUDT4P1 and GRIK2 as unique to limb muscles of Black patients with CLI. This represents a critical first step in better understanding the transcriptional program similarities and differences between Black and White patients in the setting of amputations related to CLI and provides a promising start for therapeutic development in this population.

Medical therapy for cardiovascular and limb-related risk reduction in critical limb ischemia.

Critical limb ischemia (CLI) constitutes the most advanced form of peripheral artery disease (PAD) and is characterized by ischemic rest pain, tissue loss and/or gangrene. Optimized medical care and risk factor modification in addition to revascularization could reduce the incidence of cardiovascular events and major adverse limb events, improving patients' quality of life and promising higher survival rates. Adequate adherence to cardioprotective medications, including antithrombotic therapy (e.g., antiplatelets, anticoagulants), cholesterol-lowering agents (e.g., statins, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors), angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs), and smoking cessation should be strongly encouraged for patients with CLI. This review examines these guideline-recommended therapies in terms of cardiovascular and limb-related risk reduction in patients with CLI.

Combined Superficial and Deep Venous Arterialization in No-Option Critical Limb Ischemia: Case Report.

The management of peripheral artery disease with no revascularization options can be challenging due to the very limited treatment options available and the high rate of major amputation which is linked to increased mortality and poor quality of life. Using a distal venous bed as an alternative bypass runoff seems to be a viable option when arterial reconstruction is not feasible. We report our experience with distal venous arterialization for limb salvage in non-reconstructable critical limb ischemia and describe the configuration used to achieve venosome directed revascularization in a patient with concomitant varicose veins.

Assessing health-related quality of life among patients with peripheral artery disease: A review of the literature and focus on patient-reported outcome measures.

Peripheral artery disease (PAD) is a progressive atherosclerotic disease associated with high rates of morbidity and mortality. Symptomatic PAD typically presents with claudication, and symptom severity strongly associates with reduced health-related quality of life (HRQoL). Existing treatment strategies for PAD are aimed at reducing symptom severity and improving functional outcomes. However, there is a need to incorporate patient-reported outcome measures (PROMs) into PAD treatment and research in order to provide more patient-centered care. This review will discuss the impact of PAD on HRQoL, existing PROMs available to assess PAD-related HRQoL, utilization of PROMs in research studies and registries, and challenges and solutions related to the integration of PROMs into research and clinical settings.